package com.wujunshen.algorithm.leetcode.depth.first.search;

/**
 * @author frank woo(吴峻申) <br>
 *     email:<a href="mailto:frank_wjs@hotmail.com">frank_wjs@hotmail.com</a> <br>
 * @date 2022/7/25 16:55<br>
 */
public class 岛屿数量 {
  public int numIslands(char[][] grid) {
    int count = 0;
    for (int i = 0; i < grid.length; i++) {
      for (int j = 0; j < grid[0].length; j++) {
        if (grid[i][j] == '1') {
          dfs(grid, i, j);
          count++;
        }
      }
    }
    return count;
  }

  private void dfs(char[][] grid, int i, int j) {
    if (i < 0 || j < 0 || i >= grid.length || j >= grid[0].length || grid[i][j] == '0') {
      return;
    }
    grid[i][j] = '0';
    dfs(grid, i + 1, j);
    dfs(grid, i, j + 1);
    dfs(grid, i - 1, j);
    dfs(grid, i, j - 1);
  }
}
